Structural Defects in Thick Ingaas Layers Grown by Lpee on Partially Masked GaAs Substrates

Abstract

AbstractDefect formation in thick InxGa1-xAs layers, 0.06 ≤ x ≤ 0.17, grown by liquid phase electroepitaxy (LPEE) on partially masked GaAs substrates has been studied. The InxGa1-xAs ingots were 6 mm in thickness and, in some cases, more than 53 mm long in one direction. Prior to the LPEE growth, a thin SiO2 layer was deposited on the (100) oriented GaAs substrate by plasma enhanced chemical vapor deposition (PECVD), and patterned by photolithography with oxide free seeding windows of different geometry. The growth of a ternary crystal from a slightly supercooled melt originated in the form of islands within the window areas and extended laterally over the SiO2 layer to result, as the growth proceeded by LPEE, in a continuous layer with no apparent boundaries between merging islands. The two main structural defects have been identified in these compositionally uniform ternary crystals: microtwins and microcracks. They were found to result from the crystal/substrate misfit stress, when insufficiently suppressed by the SiO2 layer, and/or from improper seeding window geometry. The microcrack and microtwin formation in large diameter InxGa1-xAs crystals has been suppressed by the right choice of the seeding window geometry as well as by minimizing damage to the SiO2 layer caused by the H2 atmosphere and high growth temperature.